The present invention relates to an automatic ignition control system of an engine used with an outboard motor for small marine vessels.
In stopping a small marine vessel or the like automatically upon detection of the engine thereof overheated in operation, an abrupt engine stop may subject the hull to a great shock by sudden deceleration due to the resistance from the water surface. In view of this, a method has been suggested to reduce the engine speed by stopping the ignition of a part of cylinders when an engine overheat is detected. (JP-A No. 57-10772). If the number of cylinders is small or depending on the type of the engine involved, however, the engine speed sharply decreases undesirably without smooth deceleration of a cruising vessel.
In order to solve this problem, a device has also been suggested which comprises a temperature detector for detecting an overheated condition of an internal combustion engine and a circuit adapted to oscillate in response to an overheated condition of the engine, wherein the ignition is intermittently stopped for deceleration in accordance with the output of the oscillation circuit under an overheated condition of the engine (See JP-A No. 58-2471).
Although this device provides means for smooth engine deceleration, the engine is decelerated according to a uniform pattern. In applications to small marine vessels or the like with various hull resistances (resistances between hull and water surface), therefore, a deceleration of the hull would be too early or too late, thereby leading to the disadvantage that an elaborate consideration is required in setting a deceleration pattern.